2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 16
Presentation Time: 1:30 PM-5:30 PM


HARLOW, George E., Department of Earth and Planetary Sciences, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, MURPHY, A. Reg, Museum of Antigua and Barbuda, P.O. Box 312, St. John's, Antigua, HOZJAN, David J., Overburden Drilling Management, 107-15 Capella Court, Nepean, ON K2E 7X1, Canada, DE MILLE, Christy N., Dept. Archaeology, University of Calgary, Calgary, AB T2N 1N4, Canada and LEVINSON, Alfred A., Dept. Geology & Geophysics, University of Calgary, Calgary, AB T2N 1N4, Canada, gharlow@amnh.org

Excavation of ornamental and gem materials from workshop sites on the island of Antigua, West Indies, also uncovered jade celts and fragments thereof.  All are jadeite jades (jadeitites), like jades from Mesoamerica.  The Antigua sites date to the Saladoid period (ca. 250-500 AD), roughly equivalent to late Formative to early pre-Classic period for Mesoamerican cultures, and reveal “jades” used in a context – decorative celt – well developed by Mesoamericans some 3100 km to the West.  Ten of these jade artifacts were examined by a combination of mineralogical and petrographic techniques to determine their mineral constituents, mineral compositions, and petrographic textures and place them in a context of possible sources among worldwide sources of jadeite jade.

      The common assemblage for six artifacts studied as polished sections include jadeite, omphacite, albite, a white-tan mica, quartz, zoisite/clinozoisite and titanite, with the exception of one artifact lacking albite and quartz.  Allanite was found in the cores of zoisites in two jades, and glaucophane and lawsonite, each, were observed in single jades.  The other four jades, which could not be studied as well, appear to contain comparable assemblages.  Conspicuous among the Antigua jades is the textural setting of quartz, a phase absent from jadeitites from most sources worldwide.  Quartz exists either as a secondary matrix phase around corroded jadeite grains (tiny omphacite grains in quartz decorate the boundaries of the jadeite) or as inclusions in jadeite associated with smaller omphacite regions.

      In comparison with jadeitites from 10 described occurrences worldwide, only jadeitites from south of the Motagua fault zone in Guatemala regularly contain the appropriate assemblage including white mica and quartz.  Moreover, glaucophane and lawsonite have also been observed in these jadeitites, and textures are also highly similar.  However, differences include absence of zoisite/clinozoisite and paragonite plus some divergences in pyroxene compositions in Guatemalan jadeitites from Antigua jades.  Although Guatemala is a reasonable source for the Antigua jades, as-yet unknown sources in similar geological terrain (serpentinite matrix mélange) on Cuba, Hispaniola, or Jamaica cannot be ruled out.